Integrated device for orienting an object according to a given spatial orientation and method for manufacturing the same

ABSTRACT

There is disclosed an integrated device for orienting an object according to a given spatial orientation comprising a frame and a supporting member connected thereto and adapted for supporting a portion of the object. The integrated device comprises a plurality of fluid actuated devices integrally molded and joined together through a joining portion to form an integral unit for displacing the supporting member with respect to the frame. Each fluid actuated device is actuatable between a first position wherein the device has a first length and a second position wherein the device has a second length. The integrated device comprises an actuation mechanism for actuating each fluid actuated device between the first position and the second position to enable displacing the supporting member with respect to the frame, thereby orienting the object according to the given spatial orientation. The integrated device may be of particular interest in the medical sector as a medical object manipulator for reaching a given target in an anatomical structure. A manufacturing method is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Patent ApplicationSer. No. 61/373,046 filed on Aug. 12, 2010 and entitled “DEVICE ANDINTEGRATED DEVICE FOR ORIENTING AN OBJECT ACCORDING TO A GIVEN SPATIALORIENTATION”, the specification of which is hereby incorporated byreference.

This application also claims priority of Canadian Patent Applicationserial number 2,713,053 filed on Aug. 12, 2010 and entitled “DEVICE FORORIENTING AN OBJECT ACCORDING TO A GIVEN SPATIAL ORIENTATION”, thespecification of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to the placing and the orientation of anobject and more particularly relates to an integrated device fororienting an object according to a given spatial orientation. The devicemay have several applications such as in the medical field for providinga needle manipulator for example. The device may be used for reaching agiven target in an anatomical structure with a suitable accuracy, forexample in the treatment and/or diagnosis of prostate cancer.

BACKGROUND OF THE INVENTION

Robot-assisted techniques are today widely used in the medical sector,for example for intervention and diagnosis purposes.

Magnetic Resonance Imaging (MRI) and other various imaging techniquesare also used for early diagnostic of cancers since MRI may helpimproving tumor perceptibility, while helping to target smaller tumorduring biopsy or treatment.

Even if imaging techniques are well suited for detecting most of tumors,biopsies are generally still required for analyzing the malignancy ofthe tumor.

For example, a TransRectal UltraSound (TRUS) system may be used toperform a guided biopsy of the prostate in order to diagnose themalignancy of the tumor and its capacity to spread. TRUS images obtainedwith an ultrasound probe guide a physician inserting tiny radioactiveseeds into the prostate during a transperinal brachytherapy. Aperforated template is generally used to guide the physician during theinsertion of the needle.

Unfortunately, TRUS offers limited contrast between tumors and healthyprostatic tissues, thereby inhibiting the identification of small tumorswith diameter below 5 mm. This limits the efficiency of the biopsy,which is of great disadvantage. In fact, at least 20 percent ofTRUS-guided prostate biopsy results in a false negative diagnosis, whichimplies that the cancer will go untreated, continue to evolve and spreadif malignant.

Magnetic Resonance Imaging (MRI) systems may offer higher tumorperceptibility than standard TRUS procedures. However, MRI guidanceimplies to work in a specific environment. Indeed, typical clinical MRIsystems generate magnetic fields ranging from 0.5 Tesla to 7 Tesla,hence no ferromagnetic objects can be introduced inside the MRIoperating room since they would easily become dangerous projectiles.Moreover, MRI systems offer a very limited access to the patient,specially the closed-bore system.

Several MRI guided robots using MRI images have been proposed forbreast, brain and prostate cancer treatments. For example, in the caseof prostate treatment, a 6 Degree Of Freedom (DOF) robotic arm equippedwith MRI compatible ultrasonic motors has been proposed for needleguidance procedures. However, they contain conducting materials creatingEddy currents which may interfere with the MRI magnetic field, thusgenerating image artifacts, which is of great disadvantage.

Pneumatic systems made with all-plastic components have also beenproposed for offering optimal MRI compatibility. MRI-compatiblepneumatic step motors have been developed and integrated to amanipulator in order to move a 6 DOF robot. The proposed step motors usepiezoelectric elements to control a compressed air flow while themanipulator's position is measured by MRI-compatible optical encoders.Many parts are involved in this complex design and step motors mightskip steps and lose accuracy, which is of great disadvantage.

A different 6 DOF approach using linear pneumatic cylinders has alsobeen proposed. In this system, the cylinders are actuated by pneumaticproportional pressure regulator valves controlled by piezoelectricelements. The pressure control system is located at the foot of the bedin order to limit non-linearity caused by air compressibility. To evenreduce the non-linearity, special low friction cylinders may be used butit increases the cost of the system. Moreover, a complex control systemshould be used, which even increase the complexity and cost of thesystem.

It would therefore be desirable to provide an object manipulator thatwould reduce at least one of the above-mentioned drawbacks.

BRIEF SUMMARY

Accordingly, there is disclosed an integrated device for orienting anobject according to a given spatial orientation, the device comprising aframe and a supporting member adapted for supporting a portion of theobject, the supporting member being operatively connected to the frame.The integrated device comprises a plurality of fluid actuated devicesintegrally molded and joined together through a joining portion to forman integral unit. Each of the fluid actuated devices has a first endoperatively connected to the frame and a second end operativelyconnected to the supporting member. Each of the fluid actuated devicesis actuatable between a first position wherein the device has a firstlength and a second position wherein the device has a second length. Theintegrated device comprises an actuation mechanism comprising aplurality of actuating valves, each being respectively operativelyconnected to a corresponding fluid actuated device for actuating thecorresponding fluid actuated device between the first position and thesecond position. An actuation of at least one of the fluid actuateddevices enables to displace the supporting member with respect to theframe to thereby orient the object according to the given spatialorientation.

The integrated device for orienting may be of particular interest as anobject manipulator for attaining a given target with a suitable accuracyin a structure extending proximate the integrated device, which is ofgreat advantage.

The integrated device for orienting may be a compact device well suitedfor use in environment wherein space is very limited, such as in a MRIsystem for example, which is of great advantage.

The integrated device for orienting may be manufactured at a cost lowerthan prior art devices for orienting an object while enabling a suitableaccuracy, which is of great advantage. Indeed, the embedding of thefluid actuated devices in an integral unit may help reducingmanufacturing and assembly errors, therefore improving the accuracy ofthe whole integrated device.

Moreover, the integrated device for orienting may be simple to operateand may produce suitable force level to reach the required stiffness,which is of great advantage for providing a suitable accuracy in thepositioning of the object with respect to a neighboring structure.

In one embodiment, the integrated device for orienting is MagneticResonance Imaging (MRI) compatible.

This is of great advantage since the integrated device may be used in anMRI environment.

In one embodiment, the second length of each of the fluid actuateddevices is longer than the first length thereof and each of the fluidactuated devices comprises a bistable fluid actuated device.

In one embodiment, each of the actuating valves comprises a bistablevalve and the actuation mechanism is pneumatically actuated.

In one embodiment, the frame, the supporting member, the plurality offluid actuated devices and the actuation mechanism are made fromnon-electrically conducting materials.

In one embodiment, the frame has a circular hollow shape and thesupporting member is mounted inside the frame.

In one embodiment, the plurality of fluid actuated devices isdistributed in a parallel array in a star-like shape. The joiningportion extends centrally in the star like shape and is adapted formounting with the supporting member.

In one embodiment, the first end of each of the fluid actuated devicescomprises an attaching element integrally molded therewith and adaptedfor attaching to a corresponding attaching element provided on theframe.

In a further embodiment, the attaching element of the first end of eachof the fluid actuated devices comprises a flange.

In one embodiment, each of the attaching elements provided on the framecomprises a wall aperture for receiving therein the flange of acorresponding fluid actuated device and two compression plates adaptedfor receiving the flange therebetween and for mounting to the frame.

In a further embodiment, the second end of each of the fluid actuateddevices is integrally molded to the joining portion.

In one embodiment, the integral unit comprises a polymer material. In afurther embodiment, the polymer material is selected from a groupconsisting of polyurethane rubber, silicon, natural rubber and acrylic.

In one embodiment, each of the fluid actuated devices comprises alongitudinal operating body and at least one inner radial reinforcementrib distributed therealong. In a further embodiment, each of the atleast one inner radial reinforcement rib is integrally molded with theintegral unit.

In yet a further embodiment, a reinforcement rib to membrane lengthratio is of about 3/8, and sections extending between two consecutiveribs have a length corresponding to twice a thickness of a wall of theoperating body.

In one embodiment, each of the fluid actuated devices comprises alongitudinal operating body and at least one reinforcement ringextending therearound.

In another embodiment, each of the fluid actuated devices is mounted ona given plane for displacing the supporting member on the plane. Theintegrated device further comprising an additional plurality of fluidactuated devices arranged on a second plane spaced-apart from the givenplane and an additional supporting member mounted on the second planefor supporting at least another portion of the object.

In one embodiment, the integrated device for orienting further comprisesa control unit operatively connected to the actuation mechanism forcontrolling the actuation of each of the fluid actuated devices Theintegrated device for orienting further comprises a position sensoroperatively connected to the control unit for sensing an actual positionof at least one of the supporting member and a tip of the object.

In one embodiment, the position sensor comprises a Dielectric ElastomerActuator (DEA) sensor.

In another embodiment, the position sensor comprises a three degree offreedom DEA sensor based on capacitance measurement.

In a further embodiment, the DEA sensor comprises a rigid circular outerframe and an array of sector-shaped compliant electrodes attachedthereto, the DEA sensor further comprising an inner mounting ringattached to each compliant electrode for receiving a portion of theobject therein.

In one embodiment, the DEA sensor comprises a polymer material selectedfrom a group consisting of silicon and acrylic.

In one embodiment, each of the actuating valves comprises a DielectricElastomer Actuator (DEA).

In another embodiment, each of the actuating valves comprises ajet-valve driven by a bistable rotary Dielectric Elastomer Actuator(DEA).

In a further embodiment, each of the actuating valves comprises a valvebody and a jet assembly mounted with the valve body. Each of theactuating valves also comprises a bistable rotary DEA mounted with thevalve body for operating the jet assembly. The bistable rotary DEAcomprises a rigid frame and a moving element having first and secondends, the first end being pivotally attached to the rigid frame forenabling pivoting of the moving element between a first position and asecond position thereof. The bistable rotary DEA comprises a first and asecond DEA films, each being attached between the second end of theactuating element and the rigid frame in a facing antagonisticrelationship in a pre-stretched state. An actuation of a correspondingone of the DEA films enables rotating the moving element between thefirst and the second position.

In another embodiment, the actuating valves are embedded in anintegrated polymer air valves stack.

In another embodiment, the integrated device is operated according to abinary control method.

In one embodiment, the plurality of fluid actuated devices isoperatively connected between the frame and the supporting member and isadapted to enable an elastically averaged positioning of the supportingmember.

In one embodiment, the object comprises a medical device.

In another embodiment, the object is selected from a group consisting ofa medical needle, a trocart and an electrode.

In still another embodiment, the object comprises a medical device forinsertion of a therapeutic agent into an anatomical structure, thetherapeutic agent being selected from a group consisting of aradioactive material, a cryogenic agent and a chemotherapy agent.

According to another aspect, there is disclosed the use of theintegrated device for orienting an object as previously described, forattaining a given target in an anatomical structure extending proximatethe integrated device.

According to another aspect, there is disclosed the use of theintegrated device for orienting an object as previously described, fororienting an articulated arm.

According to another aspect, there is disclosed a DEA valve comprising avalve body, a jet assembly mounted with the valve body and a bistablerotary DEA mounted with the valve body for operating the jet assembly.The bistable rotary DEA comprises a rigid frame and a moving elementhaving first and second ends. The first end is pivotally attached to therigid frame for enabling pivoting of the moving element between a firstposition and a second position thereof. The bistable rotary DEA alsocomprises a first and a second DEA films, each being attached betweenthe second end of the actuating element and the rigid frame in a facingantagonistic relationship in a pre-stretched state. An actuation of acorresponding one of the DEA films enables rotating the moving elementbetween the first and the second position.

According to another aspect, there is disclosed a method formanufacturing an integral molded unit comprising a plurality of fluidactuated devices embedded therein. The method comprises providing a moldcomprising a plurality of molding cavities for respectively molding theplurality of fluid actuated devices; mounting at least one wax insert onan elongated rod to provide a mounted rod; mounting a correspondingmounted rod in each of the plurality of molding cavities; providing apolymer material mix; inserting the polymer material mix in the mold;curing the inserted polymer material mix to form the integral moldedunit; removing the integral molded unit from the mold; heating theintegral molded unit at a given heating temperature for melting each ofthe at least one wax insert; removing the rods from the integral moldedunit, each removed rod providing an inlet hole in the correspondingmolded fluid actuated device; and removing the melted wax from each ofthe fluid actuated devices through the corresponding inlet hole.

In one embodiment, the method further comprises putting the integralmolded unit at rest during a predetermined resting period before usethereof. In a further embodiment, the resting period is 7 days.

In one embodiment, the polymer mix comprises silicone.

In one embodiment, the inserting of the polymer material mix comprisespouring the polymer material mix in the mold.

In another embodiment, the inserting of the polymer material mixcomprises injecting the polymer material mix in the mold with a syringe.

In one embodiment, the curing of the inserted polymer material mix isperformed at room temperature.

In one embodiment, the curing of the inserted polymer material mix isperformed during a given curing period ranging from 6 hours to 10 hours.

In one embodiment, the heating of the integral molded unit is performedduring a heating period ranging from 30 MN to 50 MN.

In one embodiment, the given heating temperature ranges between 130 and150 degrees.

In a further embodiment, the at least one wax insert comprises aplurality of wax inserts mounted in a space-apart relationship forenabling forming an inner integrally molded reinforcement rib betweentwo adjacent wax inserts.

In still a further embodiment, the mounting of at least one wax inserton an elongated rod further comprises mounting a first and a secondpermanent end inserts at each end of the corresponding mounting rod.

According to another aspect, there is also disclosed a binary controlmethod for controlling an operation of the integrated device fororienting. This method is of great advantage for reducing cost andcomplexity of the integrated device and operation thereof.

According to another aspect, there is also disclosed a calibrationmethod for calibrating the integrated device for orienting, which is ofgreat advantage for reducing the positioning error thereof.

These and other objects, advantages and features of the presentinvention will become more apparent to those skilled in the art uponreading the details of the invention more fully set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be readily understood, embodiments ofthe invention are illustrated by way of example in the accompanyingdrawings.

FIG. 1 is a perspective view of a portion of an integrated device fororienting an object according to a given spatial orientation, accordingto one embodiment.

FIG. 2 is a schematics of an embodiment of an integrated device fororienting an object according to a given spatial orientation, accordingto one embodiment.

FIG. 3 illustrates the elastically average fluid actuated deviceprinciple, in accordance with one embodiment.

FIG. 4A and FIG. 4B show an embodiment of a fluid actuated device in afirst deflated position and in a second inflated position respectively.

FIG. 5 is a front view of an integral unit of the device for orientingan object shown in FIG. 1, according to one embodiment.

FIG. 6 is a cross sectional view of a portion of the integral unit shownin FIG. 5.

FIGS. 7A and 7B are partial cross sectional perspective views of a fluidintegrated device, in a deflated position and an inflated positionrespectively, according to one embodiment.

FIG. 8 shows a Pneumatic Actuated Muscle (PAM), according to oneembodiment.

FIG. 9 illustrates an integrated polymer unit comprising 6 fluidactuated devices, according to one embodiment.

FIG. 10 illustrates a polymer Dielectric Elastomer Actuator (DEA)sensor, according to one embodiment.

FIG. 11 shows an integrated device for orienting an object according toa given orientation, according to another embodiment.

FIG. 12 illustrates the device of FIG. 11 used in a close bore MRIsystem.

FIGS. 13A to 13C show a nominal workspace and two calibrated workspaces,according to one embodiment.

FIG. 14A is a perspective view of a Dielectric Elastomer Actuator (DEA)rotary jet valve, according to one embodiment.

FIG. 14B is a cross sectional view of the DEA rotary jet valve shown inFIG. 14A.

FIG. 15A is a perspective view of a rotary DEA actuator, according toone embodiment.

FIG. 15B is a schematics view of the rotary DEA actuator shown in FIG.15A.

FIG. 15C is a graph plotting the torque applied on the hinge pivot ofthe rotary DEA actuator shown in FIGS. 15A and 15B.

FIG. 16 is a graph illustrating trajectories followed by an end effectorduring an actuation change, according to one embodiment.

FIG. 17 is a flow chart of a method for manufacturing an integral moldedunit comprising a plurality of fluid actuated devices embedded therein,in accordance with one embodiment.

Further details of the invention and its advantages will be apparentfrom the detailed description included below.

DETAILED DESCRIPTION

In the following description of the embodiments, references to theaccompanying drawings are by way of illustration of examples by whichthe invention may be practiced. It will be understood that various otherembodiments may be made and used without departing from the scope of theinvention disclosed.

The invention concerns an integrated device for orienting an objectaccording to a given spatial orientation which may be used in a greatvariety of applications such as in various medical applicationsrequiring MRI compatibility for non-limitative examples.

The integrated device may be very compact, thereby particularly wellsuited for use in environment wherein space is very limited, such as ina MRI system.

Throughout the description, the integrated device for orienting anobject will be described in the particular application of prostatecancer treatment but the skilled addressee should appreciate that thedevice may be used in many applications where medical tool orientationand placement is key for the success of the treatment, as it will becomeapparent below.

The skilled addressee will also appreciate that the integrated devicefor orienting may also be used in a great variety of other applicationswherein ferromagnetic compatibility is required or in a flammableenvironment, as it will also become apparent below.

Referring to FIGS. 1 and 2, an embodiment of an integrated device 10 fororienting an object 12 according to a given spatial orientation will nowbe described. This embodiment may be of great interest for orienting amedical object according to a given spatial orientation or direction,for example for reaching specific targets in an anatomical structure(not shown) with a suitable accuracy, as it will become apparent below.

The integrated device 10 comprises a frame 14 and a supporting member 16adapted for supporting at least a portion of the object 12. Thesupporting member 16 is operatively connected to the frame 14, asdetailed below. In the illustrated embodiment, the frame 14 has acircular hollow shape and the supporting member 16 is mounted inside theframe 14, as explained below. Still in the illustrated embodiment, theobject 12 comprises a medical needle. The skilled addressee will howeverappreciate that various other arrangements may be considered.

As better shown in FIGS. 1 and 5, the integrated device 10 comprises aplurality of fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 eintegrally molded and joined together through a joining portion 50 toform an integral unit 52. The integral unit 52 is operatively connectedto the frame 14 and the supporting member 16 for enabling a relativemovement therebetween. Each of the fluid actuated devices 18 a, 18 b, 18c, 18 d, 18 e has a first end 20 operatively connected to the frame 14and a second end 22 operatively connected to the supporting member 16.

As illustrated in the embodiment shown in FIG. 2 which comprises 6 fluidactuated devices, each of the fluid actuated devices is actuatablebetween a first position wherein the device has a first length and asecond position wherein the device has a second length. In theillustrated embodiment, some of the fluid actuated devices extend in thefirst position while the others extend in the second position, as itwill become apparent below. FIG. 2 well illustrates how an actuation ofat least one of the fluid actuated devices enables to displace thesupporting member 16 with respect to the frame 14. The supported object12 may then be oriented according to a given spatial orientation.

Referring again to FIG. 2, the integrated device 10 for orienting alsocomprises an actuation mechanism 24 comprising a plurality of actuatingvalves 24 a, 24 b, 24 c, 24 d, 24 e, 24 f, each being respectivelyoperatively connected to a corresponding fluid actuated device 18 a, 18b, 18 c, 18 d, 18 e, 18 f for actuating the corresponding fluid actuateddevice between the first position and the second position.

In the illustrated embodiment, the supporting member 16 is held inposition with respect to the frame 14 via the fluid actuated devices 18a, 18 b, 18 c, 18 d, 18 e, 18 f mounted therebetween but it should bementioned that other arrangements may be considered.

The skilled addressee will appreciate that in the embodiment illustratedin FIG. 2, the fluid actuated devices 18 a to 18 f are schematicallyillustrated as elastic springs but this schematic representation shouldnot be understood as limited to the use of springs, as it will becomeapparent below.

Embedding the plurality of fluid actuated devices in an integral moldedunit 52 may be of great advantage since it may enable to reduce theoverall volume of the integrated device 10 which may then be used inlimited spaces such as inside a closed-bore MRI system. In the meantime,it enables producing suitable high volumetric forces while obtainingsatisfactory system stiffness, as detailed below.

Moreover, specifically designed molds may be used to mold the integralunit 52, as detailed below. Such a technique may provide an accurate andrepeatable manufacturing of the integral unit 52, which is of greatadvantage for improving overall performances of the integrated device10.

Indeed, “Design of a Binary Needle Manipulator Using Elastically AverageAir Muscles for Prostate Cancer Treatments” ASME San Diego, Calif., USA,Aug. 30, 2009, by the same inventors, presents a preliminary analyticalmodel and a corresponding sensitivity analysis evaluating the impact ofkey design parameters variations such as initial length, materialconstants, pressure, wall thickness and initial radius of non-integratedfluid actuated devices. The analysis shows that the manufacturingprocess of the fluid actuated devices may be critical in achieving theneeded accuracy.

Such a molding technique may also help reducing manufacturing costs aswell as operating costs, as it will become apparent below. This is ofgreat advantage since it may provide a cost-effective solution forsimple procedures inside an MRI bore.

The embodiment shown in FIG. 1 is of great advantage since the dynamicmounting of the fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 ebetween the frame 14 and the supporting member 16 enables an elasticallyaveraged positioning of the supporting member, as detailed thereinafter.

FIG. 3 shows the basic operating principle of an elastically averagedbinary fluid actuated device 18 a in a single degree of freedom (u)system. Forces applied on the end effector (F_(A) and F_(B)) by thefluid actuated devices, along with the actuation pressure (P) states arepresented by Free-Body Diagrams (FBD).

As it should become apparent to the skilled addressee throughout thereading of the present description, using an integral unit 52 embeddingthe fluid actuated devices may be of great interest since it may enablea greater controlled elastically averaged positioning of the supportingmember 16. Indeed, controlled elastically averaged positioning of thesupporting member 16 may be obtained with independent fluid actuateddevices. However, as it should become apparent to the skilled addressee,an integrally molded unit may enable a better prediction of reachablepositions as well as a better control as variations among the actuatorsare limited by the manufacturing process. It is possible to achieveelastically averaged positioning and control with a non-integral unit,but lower overall precision may be expected due to higher variability inthe manufacturing of individual actuators.

FIGS. 4A and 4B schematically illustrate an embodiment of a fluidactuated device 18 a comprising an upper rigid fixture 42, a lower rigidfixture 44 and a deformable hollow membrane 46 extending therebetween.FIG. 4A shows the fluid actuated device 18 a in the first position,which is a deflated position, while FIG. 4B shows the fluid actuateddevice 18 a in the second position, which is an inflated position. Thefluid actuated device 18 a has a first length in the first position anda second length longer than the first length in the second position. Asillustrated, when the fluid actuated device 18 a is actuated, fluid isforced inside the membrane 46 which deformed under the pressure of thefluid. The membrane 46 deforms axially but also longitudinally. Sinceone of the upper and lower fixtures 42, 44 is attached to the frame 14,this longitudinal deformation pushes on the other fixture connected tothe supporting member 16, thereby moving the supporting member 16accordingly. As shown, in this embodiment, when actuated, the fluidactuated device 18 a has a length longer than its initial length, i.e.it works in extension.

FIG. 5 illustrates the integral molded unit 52 shown in FIG. 1. Theintegral unit 52 comprises 5 integrated fluid actuated devices 18 a, 18b, 18 c, 18 d, 18 e distributed in a parallel array and molded togetherin a star-like shape with the joining portion 50 extending in the middleof the star like shape. The central joining portion 50 may be used formounting the integral unit 52 with the frame 14 and the supportingmember 16, as detailed below.

The first end 20 of each of the fluid actuated devices 18 a, 18 b, 18 c,18 d, 18 e comprises an attaching element 54 integrally molded therewithand adapted for attaching to a corresponding attaching element providedon the frame. In the illustrated embodiment, the attaching element 54 ofeach of the fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 ecomprises a flange 56 but various other arrangements may be considered.The second end 22 of each of the fluid actuated devices is integrallymolded to the joining portion 50, thereby providing an integrally moldedunit 52.

Referring again to FIG. 1, in the illustrated embodiment, the integralunit 52 is fixed to the frame 16 through the attaching elements 54 ofthe fluids actuated devices. The frame 14 is made out of a fiberglasstube in order to provide adequate rigidity and precise localization ofthe fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 e. In thisembodiment, the fiberglass tube frame 14 is provided with wall apertures30 suitably positioned for receiving therein the attaching elements 54of the fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 e. Twocompression plates 32 a, 32 b are used for squeezing the flange 56 andretain it to the frame 14.

The molded fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 e arelinked together through the central joining portion 50 and localized bya central rod 34 and a disks system 36 mounted with the central joiningportion 50. Disks are linked together by carbon fiber rods to ensureproper alignment. The central rod 34 is meant to localize each fluidactuated device 18 a, 18 b, 18 c, 18 d, 18 e of the integral unit 52relatively to each other. The skilled addressee will appreciate thatvarious other arrangements may be considered for mounting the integralunit 52 with the frame 14.

In this embodiment, as it should become apparent to the skilledaddressee, the fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 e maypivot at each end around their thinner section without friction.

Silicones, such as Dow Corning HSII or Sylgard, may be used for formingthe integral unit 52 since they may be easily molded on complex shapesand they may reach high strains to maximize the displacement of thepneumatic cells. Silastic V-RTV Silicone from Dow Corning mayalternatively be used. Another hyper-elastic material selected, forexample, from a group consisting of polyurethane rubber, silicon,acrylic, natural rubber or any combination thereof may also be usedaccording to a given application. The skilled addressee will alsoappreciate that other materials having a suitable elasticity andenabling a suitable temporary deformation under the pressure of a fluidmay be considered. In one embodiment, the hyper-elastic materialcomprises a low visco-elastic material.

Such an integral polymer unit 52 may help reducing manufacturing andassembly errors, thereby resulting in improved accuracy, lesscomponents, and smaller size, which is of great advantage.

As known to the skilled addressee, there are two opposite deformationmechanisms in a fluid actuated device working in extension. First, thepressure inside the fluid actuated device creates a force on theextremities thereof, making it extends. Then, the pressure also deformsthe membrane of the fluid actuated device, which makes the deviceshortens.

In order to improve the performances of the fluid actuated devices 18 a,18 b, 18 c, 18 d, 18 e, these devices may be reinforced with a ring orradial ribs in one embodiment. These ribs may limit the radial inflationof the membrane and maximize the extension thereof.

FIG. 6 illustrates an integral unit 52 wherein the fluid actuateddevices 18 a, 18 b, 18 c are each provided with three internal moldedribs 60 acting as radial reinforcements.

To further improve the performances of the fluid actuated devices, inone embodiment, the membrane thickness may be chosen according to aspecific application, as explained below.

Indeed, the membrane thickness should be thick enough to limit theradial inflation thereof when actuated. In the same time, the membraneshould be thin enough and long enough to enable a suitable longitudinaldeformation and a suitable axial deformation under the created force.

From simulations and experiment, it has been found that, in oneembodiment, the reinforcement to membrane length ratio may beapproximately 3/8, with each membrane section extending between twoconsecutive ribs being twice the membrane thickness. The skilledaddressee will nevertheless appreciate that other arrangements may beconsidered for a given application.

The skilled addressee will appreciate that as an increased fluidactuated device diameter increases the membrane area exposed topressure, thus increasing the radial deformation thereof. Thereinforcement to membrane length ratio and/or the membrane thickness maythen be increased for an increased fluid actuated device diameter.

FIGS. 7A and 7B show a fluid actuated device 18 a in a non-actuatedstate and an actuated state respectively, according to one embodiment.The illustrated fluid actuated device 18 a is made of V-RTV Silicone,has 4 membrane sections 70 of 8 mm each and three 3.175 mm reinforcementribs 60 between them. Membrane thickness is 4 mm and external diameteris 25.4 mm. The device 18 a has a length of 41.5 mm and provides anelongation of at least 10 mm under a 35 PSI pressure.

FIG. 9 shows another embodiment of a molded integral unit 90 embedding 6integrated fluid actuated devices 92 distributed in a parallel array andmolded together in a star-like shape. In this embodiment, the joiningportion 94 is a hexagonal portion extending between the fluid actuateddevices 92 and has a hole 96 in the middle thereof for mountingpurposes.

A molded unit with a joining portion of increased volume extendingbetween the fluid actuated devices 92 may provide an improved stiffnessto the unit, which may be of great advantage for a given application.Larger fluid actuated devices may also be used to increase stiffness ofthe unit.

As illustrated, reinforcing ring-like fibers 98 may be provided alongeach of the fluid actuated devices 92 for improving performancesthereof, as detailed above.

In the embodiment illustrated in FIG. 9, the 6 fluid actuated devices 92are equally distributed and therefore, each is facing another fluidactuated device. In the embodiment illustrated in FIG. 1, the system'ssymmetry is broken by providing 5 fluid actuated devices. The asymmetrymay provide a more uniform workspace, without a repeating pattern, asexplained therein.

Referring now to FIG. 8, there is shown another embodiment of a singlefluid actuated device, also called a Pneumatic Actuated Muscle (PAM)100, which has been used for experimentation purposes. The illustratedPAM 100 comprises a latex tube 102 those wall thickness is 3.125 mm anda plurality of rubber membranes 104 those total wall thickness is about0.8 mm for covering the latex tube 102. This may be of great advantageto reduce the degradation of the latex, which is typically affected byultraviolet light, thus maximize the lifetime of the latex.

In the illustrated embodiment, a Kapton™ ring 106 is fixed at mid lengthbetween the latex and the rubber membrane. The circumferentialconstraint provided by the Kapton™ ring 106 increases the maximal usablepressure, and thus the maximum axial displacement that the PAM 100 canwithstand before it reaches instability (−275 kPa). Actuation pressuremay be set to 170 kPa for example.

In this embodiment, an attaching element 108 is provided at each end ofthe fluid actuated device 100. These attaching elements are made ofDelrin™ in which a plastic ball joint is press-fitted to provide threeangular Degrees Of Freedom (DOE).

The illustrated fluid actuated device uses a single radial reinforcementring and extends when pressure is applied. Hence, the fluid actuateddevice must remain under tensile load, as shown in FIG. 3, since theywould otherwise buckle due to their pivot mounts, as it should beapparent to the skilled addressee.

Referring again to FIG. 2, in a further embodiment, the integrateddevice 10 for orienting an object 12 further comprises a control unit 26operatively connected to the actuation mechanism for controlling theactuation of each of the fluid actuated devices 18 a, 18 b, 18 c, 18 d,18 e, 18 f.

In one embodiment, the actuation mechanism 24 is pneumatically actuated.In a further embodiment, the device 10 for orienting is operated withpressurized air. This is of great advantage when the device 10 fororienting an object 12 is used in an hospital or a similar environmentsince pressurized air is generally already available. The skilledaddressee will nevertheless appreciate that other fluid may be used foroperating the device 10, according to a given application.

In one embodiment, the device 10 for orienting is operated according toa binary mode. In other words, each of the fluid actuated devices 18 a,18 b, 18 c, 18 d, 18 e, 18 f comprises a bistable fluid actuated devicewhich may only take two distinct states. Accordingly, each of theactuating valves 24 a, 24 b, 24 c, 24 d, 24 e, 24 f comprises a bistablevalve. As it will become apparent below upon reading of the presentdescription, such a binary operating mode may be of great advantage fora given application since the actuation and the control thereof may begreatly simplified while leading to improved accuracy of the device.

For a given application, the actuation mechanism 24 may nevertheless beadapted to actuate each of the fluid actuated devices 18 a, 18 b, 18 c,18 d, 18 e, 18 f continuously between the first position and the secondposition. In other words, each of the fluid actuated devices 18 a, 18 b,18 c, 18 d, 18 e, 18 f may take a plurality of positions between thefirst position and the second position. In this embodiment, theactuating valves 24 a, 24 b, 24 c, 24 d, 24 e, 24 f should beconveniently chosen to enable such a continuous operating mode.

In one embodiment, the control unit 26 may operate the device 10 fororienting an object 12 according to an open loop mode while in anotherembodiment a closed loop mode may be implemented, as better detailedthereinafter.

Referring again to FIG. 2, in one embodiment, the device 10 fororienting an object 12 further comprises a position sensor 28operatively connected to the control unit 26 for sensing an actualposition of at least one of the supporting member 16 and a tip of theobject 12.

Referring now to FIG. 10, there is shown a 3 degree of freedomDielectric Elastomer Actuator (DEA) position sensor 200 which may beused in the integrated device 10 to provide feedback informationconcerning the actual position of the object 12.

The illustrated DEA sensor 200, which is based on capacitancemeasurements, comprises a rigid circular outer frame 202 and an array ofsector-shaped compliant electrodes 204 attached thereto. An innermounting ring 206 devised to receive a portion of the object 12therethrough is attached at the tip of each compliant electrode 204. Asit should become apparent, a change in the orientation of the object 12will deform the compliant electrodes 204 accordingly.

The DEA sensor 200 correlates the position of the center point of thearray of compliant electrodes 204 to their individual capacitances. Theposition of the needle end point may be found from simple kinematicsassuming a rigid needle. The illustrated embodiment has shown sensingcapabilities in non MRI-environment with precision in the order of 0.1to 1 mm. Such DEA sensor 200 may thus be used as an efficient andinexpensive MRI-compatible displacement sensor, which is of greatadvantage for reducing the cost of the integrated device.

In one embodiment, the DEA sensor 200 comprises readily availableacrylic films (VHB 4905). In another embodiment, the DEA sensor 200 ismade of silicone such as Elastosil and NUSIL CF19-2186 that have higherdielectric constants (7 vs 3 for acrylics) needed for an increasedcapacitance value and thus better tolerance to disturbances.

In a further embodiment, the DEA sensor 200 may be manufactured using aspin-coating apparatus to produce uniform silicone films, thus improvingthe sensor's repeatability and accuracy, which is of great advantage.

Although the integrated device 10 for orienting an object 12 may beoperated according to an open loop mode, it may be of great advantagefor a given application to operate the device according to a closed loopmode thanks to the position sensor 28, as apparent to the skilledaddressee. In fact, the control unit 26 may monitor the actual positionof the tip of the object 12 via the sensor 26 in order to correct forany calibration error or operating drift which may arise, as detailedbelow.

Referring again to FIG. 1 and as described above, in the illustratedembodiment, the fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 e aremounted on a given plane and form a planar integral unit. It should beunderstood that although the integral unit is planar in this embodiment,small out of plane motions may occur during the operation of theintegrated device 10. The skilled addressee will also appreciate thatother arrangements wherein the fluid actuated devices are mounted out ofplane may be considered for a given application.

In a further embodiment, as illustrated, the integrated device 10 fororienting an object 12 may further comprise an additional integral unit152 embedding an additional plurality of fluid actuated devices 18 g, 18h, 18 i, 18 j, 18 k arranged on another plane. In the illustratedembodiment, four integral units 52, 152, 252, 352, each embedding 5fluid actuated devices, are mounted inside the tubular frame 14 in aspace-apart relationship with each other with corresponding attachingflanges and compression plates, as previously described. The centraljoining portion of each of the integral unit 52, 152, 252, 352 may bemounted with the central rod 34 and the disks system 36, as detailedabove, for providing additional support to the object 12.

In the embodiment illustrated in FIG. 1, the system's symmetry is brokenby offsetting the four integral units 52, 152, 252, 352 with each other,as well shown by the mounting compression plates. This may be of greatadvantage to avoid the position's redundancy of facing fluid actuateddevices, as it should become apparent to the skilled addressee. Aspreviously stated, the asymmetry also provides a more uniform workspace,without a repeating pattern.

It should be mentioned that two important factors may affect thestiffness' behavior of the overall system. Indeed, the system can beorthotropic if the amount of actuators used is insufficient. In fact,experiments has shown that the stiffness variation may be of about 13%for a manipulator that would use two integral units of 5 fluid actuateddevices compared to about 8% when using two integral units of 7 fluidactuated devices and to about 6% when using two integral units of 9fluid actuated devices. Thus, the stiffness variation decreases as themanipulator is composed of more fluid actuated devices.

The disposition of the fluid actuated devices around the needle supportmay also affect the stiffness of the system. When using 12 fluidactuated devices, the amount of devices per planes offers thepossibility to alternatively offset the fluid actuated devices on thesame plane. When using an odd amount of fluid actuated devices perplane, such as for 10, 14 and 18 fluid actuated devices distributed intwo distinct planes for example, the offset distribution is not even andmay cause a more important modification in the stiffness behavior. Thisexplains why the stiffness of a system provided with 12 fluid actuateddevices distributed in two planes presents less variation then amanipulator having 18 fluid actuated devices. As previously mentioned,this offset may be required in some applications to break the symmetryand reduce position redundancy.

The skilled addressee will nevertheless appreciate that a singleintegral unit 52 of fluid actuated devices may be used. However, two ormore units may be preferred for a given application since it may enablea more accurate positioning of the object 12, for example a medicalneedle.

In one embodiment, the planes extend parallel to each other but otherarrangements may be considered.

In a further embodiment, a plurality of integrated devices 10 asdescribed above may be used as articulated joints and mounted in aserial arrangement to form an articulated arm (not shown), as it shouldbecome apparent to the skilled addressee throughout the reading of thepresent description. The fluid actuated devices may also be used toreplace any rotary joints in conventional articulated arm designs.

Still referring to FIG. 1, a convenient number of additional actuatingvalves is used for independently actuating each of the additional fluidactuated devices 18 g, 18 h, 18 i, 18 j, 18 k.

In the embodiment illustrated in FIG. 1, each of the integral units 52,152, 252, 352 comprises 5 fluid actuated devices but the skilledaddressee will appreciate that various other configurations may beenvisaged. For example, each integral unit may comprise from 2 to 24devices, as detailed above. Each integral unit may also comprise adifferent number of fluid actuated devices, according to a givenapplication.

In the embodiment illustrated in FIGS. 1 and 5, each of the fluidactuated devices 18 a, 18 b, 18 c, 18 d, 18 e has the same initiallength. However, in another embodiment, at least one of the fluidactuated devices 18 a, 18 b, 18 c, 18 d, 18 e may have a given firstinitial length while the remaining fluid actuated devices may have agiven second initial length longer than the first initial length whenextending in the first position. This may be of great advantage forenabling a uniform distribution of the possible positions of the tip ofthe needle in a given workspace, as further described below.

In the embodiments described above, the fluid actuated devices 18 a to18 f have been described as having an expanded length when actuated. Theskilled addressee will nevertheless appreciate that other arrangementsmay be considered. For example, in an alternative embodiment, the fluidactuated devices may have a contracted length when actuated, as welldescribed in “Pneumatic Actuating Systems for Automatic Equipment”, IgorL. Krivts, 2006.

As previously mentioned, the integrated device 10 for orienting anobject 12 may be of great interest in the medical sector forrobot-guided interventions in a MRI environment for example. In thiscase, the integrated device is adapted to be Magnetic Resonance Imaging(MRI) compatible.

Accordingly, in one embodiment, the frame 14, the supporting member 16,the integrated fluid actuated devices 18 a, 18 b, 18 c, 18 d, 18 e andthe actuation mechanism 24 are made from non-electrically conductingmaterials. The frame 14 and the supporting member 16 may be made ofplastic or fiber glass, as mentioned above. The fluid actuated devices18 a, 18 b, 18 c, 18 d, 18 e may be made from polymer materials whilethe actuation mechanism 24 may be made from plastic and polymermaterials, as it should become apparent below.

Indeed, as described below, in one embodiment, each of the actuatingvalves 24 a, 24 b, 24 c, 24 d, 24 e, 24 f may comprise a DielectricElastomer Actuator (DEA). In another embodiment, each of the actuatingvalves 24 a, 24 b, 24 c, 24 d, 24 e, 24 f may comprise a piezo-electricactuator. The skilled addressee will however appreciate that otherarrangements may be considered for providing a MRI compatible device.

As mentioned above, although the integrated device 10 for orienting aspreviously described may be useful in a great variety of application,one application is in the medical sector for manipulating and orientinga medical device in order to reach a given target in an anatomicalstructure with a suitable accuracy.

Indeed, the object 12 may comprise a medical needle for insertion intoan anatomical structure such as a prostate for a non-limitative exampleand as detailed below. In another embodiment, the object 12 may comprisea trocart or an electrode or any other medical device which has to beparticularly positioned with respect to the anatomical structure beforeinteracting therewith. For example, the medical device may be used toperform a biopsy, as known to the skilled addressee. It may also be usedfor insertion of a therapeutic agent into an anatomical structure, thetherapeutic agent being selected from a group consisting of aradioactive material, a cryogenic agent and a chemotherapy agent, aswell known in the art to which the invention pertains.

Referring now to FIGS. 11 and 12, an embodiment of an integrated binaryElastically Averaged Pneumatic Air Muscles Manipulator (EAPAMM) 300 forMRI-guided biopsy and treatment of prostate cancer will now bedescribed. The integrated manipulator 300 may enable to precisely reachsmall tumors whose diameter is less than 5 mm inside the prostate. Theintegrated manipulator 300 may be placed between the patient's legs inorder to scan the prostate. Although FIG. 12 illustrates thetransperinal approach in the lithotomic position, it should be notedthat other approaches may be implemented, as it should become apparentto the skilled addressee throughout reading the present description.

The integrated manipulator 300 is adapted to place a needle 302 in anoptimal trajectory to precisely reach small tumors identified by realtime Magnetic Resonance (MR) images, thereby improving treatmentaccuracy and reducing procedure time compared to current manualultrasound techniques, as described above.

The integrated manipulator 300 comprises an integrated device fororienting an object as previously described using two polymer integralunits 90 as better illustrated in FIG. 9, each containing 6 integratedfluid actuated devices 92 distributed according to a star-like shape.Binary control may be implemented to position the needle 302 in space,as detailed thereinafter.

The actuation mechanism comprises a stack of 12 all-polymer pneumaticvalves (not shown). A polymer position sensor 200 and associated binarycontrol (not shown) are also embedded in the integrated manipulator 300.In this embodiment, the integrated manipulator 300 is built out ofMRI-compatible material such as rubber, latex, fiberglass and Delrin™for non-limitative examples, as previously detailed.

As well illustrated in FIG. 12, the use of fluid actuated devicesintegrally molded in an integral unit may help providing a compactintegrated manipulator usable inside a closed-bore MRI system, which isof great advantage. As an exemplary embodiment, the illustratedintegrated manipulator may have an overall shape of about 190 mm×190mm×175 mm, although other arrangements may be considered.

The illustrated needle manipulator may enable a positioning of theneedle in a three dimensional workspace of 70 mm in width, 80 mm inheight and 70 mm in depth, in order to cover a complete cancerousprostate located at 60 mm away from the perineum.

The manipulator may be adapted to provide a stiffness sufficient tosustain the radial penetration loads which may be applied on the needleand may offer a suitable accuracy of about 0.7 mm, which is similar towhat other prostatic MRI compatible manipulators may offer.

In this described embodiment, the air muscles are bistable, i.e. theyhave two states, namely an inflated position when pressure is appliedand a deflated position when no pressure is applied thereto. Binarycontrol is provided by on/off spool valves that enable the manipulatorto maintain a stable position without continuous electrical energy beingsupplied to the valves, which is of great advantage since it reduces therisk of interferences with the MRI signal. These valves are driven byMRI compatible actuators such as piezoelectric or DEA actuators, asmentioned above. When inflated, the air muscles are held at constantpressure to avoid needle drift which may be caused by air pressurefluctuations, such as an air leakage. In this embodiment, aircompressibility does not influence the system's compliance as theelastic membranes are chosen to be significantly stiffer than the airvolume acting upon them.

The air muscles may be assumed to be active non-linear springs whichhave different force/deformed length profiles determined by theirgeometry and inflation pressure. In the embodiment illustrated in FIG.2, the various needle equilibrium positions are defined by the differentbinary actuation states of the overconstrained device 10. The airmuscles may be pre-stretched and designed to remain in tension for allactuation states.

As it should become apparent to the skilled addressee, the air musclesinherent compliance may help accommodating the different actuator'sstates, thereby reducing the robot's complexity and volume compared to acomplex spring assembly.

The skilled addressee will also appreciate that the integrated devicefor orienting an object as previously described may constitute an activecompliant mechanism where the compliance relieves the over-constraintimposed by the redundant parallel architecture.

Non-linear springs with decreasing stiffness may show horizontalportions in their force/deformed length curves causing local minima inthe global potential energy function. Also, these horizontal portionshave no stiffness, thus generating excessively large displacements whensubject to even the smallest perturbations. Hence, in one embodiment,the air muscles have been designed to avoid these potential issues byverifying that force/deformed length characteristic curve avoids localminima and thus low stiffness.

FIG. 13A shows all 4096 (2¹²) available discrete positions that theneedle tip of an embodiment of a binary needle manipulator may occupy ingiven conditions when using two sets of 6 fluid actuated devices. Asknown to the skilled addressee, binary systems may only reach a finiteset of points and these points should be evenly distributed in therequired workspace in some applications. It may thus be of greatadvantage to break all system symmetries. To do so, the fluid actuateddevices embedded in the integral unit may have varying initial lengthsor an angular offset with respect to one another, as previouslydescribed.

Referring now to FIGS. 11, 14A and 14B, in one embodiment, the actuationmechanism used for actuating the fluid actuated devices embedded in thetwo integral units may comprise a stack of 12 MRI-compatible DEA airvalves (not shown) for controlling the pressure states of the 12integrated fluid actuated devices. The use of an integrated stack of 12MRI-compatible DEA air valves may be of great advantage for evenreducing the volume of the overall system.

FIGS. 14A and 14B show an air valve 400 comprising a two stage jet-valve402 driven by a rotary DEA 404. The air valve 400 comprises a valve body406, a jet assembly 408 mounted with the valve body 406 and a bistablerotary DEA 404 mounted with the valve body 406 for operating the jetassembly 408. Experiments have shown that a pressure of 200 kPa at thejet air intake may be required to switch the spool position.

Typically, a DEA is composed of a polymer film, held by a rigid frame,with compliant electrodes applied on each side of the film. To actuate aDEA, high voltage is applied on the electrodes to deform the polymer bythe Maxwell forces, as known in the art. DEA's reliability is thecritical challenge since DEA have limited life when used under largestrains and high loads. However, properly designed actuators withlimited actuations strains and operating under low load may potentiallyreach 10,000 to 100,000 cycles.

The jet-valve shown in FIGS. 14A and 14B uses a rotary bistable actuatorhaving very limited actuation strain (λ=1.1). The skilled addressee willappreciate that the actuator loads are virtually null since aerodynamicforces are normal to the jet axis and thus have no moment arm, which isof great advantage. The actuator prismatic shape also offers therequired space to implement the air jet assembly, offering avolume-efficient design, which is of great advantage for providing acompact integrated device.

FIGS. 15A to 15C show a bistable rotary DEA 404 that may be used in theair valve 400 described above. In this embodiment, the rotary DEA 404comprises a rigid frame 410 and a moving element 412 having first andsecond ends 414, 416. The first end 414 is pivotally attached to therigid frame 410 for enabling pivoting of the moving element 412 betweena first position and a second position thereof. The bistable rotary DEA404 also comprises a first and a second DEA films 418, 420, each beingattached between the second end 416 of the moving element 412 and therigid frame 410 in a facing antagonistic relationship. The films 418,420 are pre-stretched in a planar state and then pushed out-of-plane byraising a hinge mechanism. As it should become apparent, an actuation ofa corresponding one of the DEA films 418, 420 enables rotating themoving element 412 between the first and the second position.

In this configuration, which is an antagonistic configuration, a linearover-the-center spring 422 may be used to gain bistability, Otherconfigurations may nevertheless be considered.

The torque generated by the actuation cells (T_(film)) holds the movingelement 412 up against a stopper 424 when no voltage is applied. Whenvoltage is applied to an actuation cell, T_(film) orientation inversesand causes the actuator to shift toward its other stable position.

The skilled addressee will note that a tradeoff between output work andactuation speed may be taken in consideration in the design of DEAs.This may be done through tuning the actuator's actuation stretches. Infact, a rotating configuration tuned for low actuation stretch(λ_(act,1)=1.1) shifts up to 15 times faster than a configuration tunedfor maximal work output. This tradeoff is valid for any DEAs usingviscoelastic polymers.

Although a preferred DEA valve has been described, the skilled addresseewill nevertheless appreciate that a piezoelectric actuator mayalternatively be used, such as a Parker Origa Tecno series actuator, asa non-limitative example. However, piezoelectric materials are expensiveand have been reported to cause image artifacts when used inside an MRIbore, even at fields of only 1.5 T. In this case, they may be placedless conveniently outside the MRI bore to reduce their impact on imagequality.

DEA valves are of great advantage since they do not have this limitationand can be placed anywhere within the MRI bore.

As previously mentioned, the position of the needle may be controlledaccording to a binary robotics approach, which is of great advantage forproviding simplicity and robustness of the overall system. Accordingly,an embodiment of a binary control method will now be described.

As previously mentioned, since only two pressure states are possible foreach actuator in binary control, the number of possible configuration is2^(n), where n is the number of fluid actuated devices (12 fluidactuated devices provide 4096 positions). A table containing allpossible orientations of the needle may be generated by a calibratedmodel and experimental measurements. In one embodiment, the calibrationmay be performed over the elastic material constants of the fluidactuated devices.

The skilled addressee will appreciate that this binary control methodeliminates the need of a low-level feedback, thus reducing costs andcomplexity, which is of great advantage.

The binary control method may be implemented as an open loop controlmode to orient the needle toward a desired target location. The targetlocation, which is selected by user, is identified on MR images. Amanipulator analytical model combined with image processing techniquesin Matlab™ or Labview™ may then select the proper binary actuation statesequence. The skilled addressee will appreciate that this control modemay be sensitive to disturbances, e.g. external forces, and errors, e.g.manipulator model errors.

Hence, in a further embodiment, a closed-loop position control methodmay be used to select the binary sequence minimizing error between thedesired target location and the actual manipulator location.

As it will become apparent to the skilled addressee, ageing or creepingeffects of the material may be mitigated with appropriate control andself-calibration, which is of great advantage.

In one embodiment, optical techniques may be used to measure actualend-effector position without affecting the manipulator. A 10 megapixelsCanon EOS 40D equipped with a 50 mm focal length f/1.4 Canon lens whichreduces edge distortion may be placed normal to a measurement windowfacing the tip of the needle to record a displacement thereof. In oneembodiment, pixels are scaled using laser engraved rectangles placed oneach side of the workspace, giving a resolution of 50 μm/pixel. Theneedle tip is located automatically by using Labview image processingtools.

As well known to the skilled addressee, accuracy is the ability of themanipulator to reach the position predicted by a model. Accuracy isexperimentally assessed by measuring the position error between themodel and the manipulator for a plurality of given actuation states.This test is in fact a validation of the predicted workspace. In oneexperiment, 100 random sequential positions are acquired. In oneembodiment of the integrated device using 12 fluid actuated devices,when using the nominal model, the accuracy is of about 5.4 mm.

A calibration of the model may then be required in order to reduce theerror. To achieve this calibration, 50 points are used to calibrate themodel and 50 others positions are used to confirm that the calibrationeffectively reduce the error on the rest of the workspace. Thiscalibration was achieved over pressure and material constantssequentially. To calibrate the model, a multiplying factor (α) wasimplemented to the nominal manufacturing parameters in the energy modeland parameter identification was achieved on all a to reduce the error.The parameter identification may be completed using an optimizationalgorithm based on the Nedler-Mead technique (Matlab fminsearch).

The workspace resulting of those calibrations are shown in FIGS. 13A to13C. The calibration has reduced the workspace's diameter of about 15 mmfor both cases. As shown, the available position density of thecalibration over pressure presents a more suitable coverage of therequired workspace than the calibration over the material constants.Nonetheless, the calibration over material constants may be moreaccurate.

Pressure may be the most sensitive parameter in the model discussedabove. Moreover, as the pressure which is to be applied to all fluidactuated devices is the same, pressure represents only one parameter tooptimize in the model, which greatly reduces the complexity of theidentification of the parameters. A first pressure calibration may showa 40% reduction of the nominal error. The parameter identificationshowed that a pressure of about 90% of the nominal value gives a betteragreement between the model and the experimental trials. In thisexperiment, the computation converged in about 4 hours to identify thisparameter.

A calibration may also be assessed on the second order Mooney-Rivlinformulation of the fluid actuated devices curve-fitted. The use ofidentification parameters on each fluid actuated device may compensatefor the geometric error that may be found therein, the materialparameter variation error between the fluid actuated devices and theactuation pressure. The optimization complexity is then increased to atotal of 48 (12×4) parameters. The results from the calibration over thematerial constants may indicate an error reduction of about 48% fromnominal values and a reduction of 13% from the calibration using thepressure. In this experiment, the solution converged after about 100hours of computation.

It should be noted that only about 1% of the total workspace was usedfor the above described calibration procedure. The number of calibrationpoints influences and improves parameter identification quality but needmore computing time. To further improve parameter identificationeffectiveness, the system geometry error (anchor points) and the airmuscles geometry errors may be treated, leading to an unpractical 96(9×12) parameters to identify.

In a further embodiment, the complete workspace may be mappedexperimentally and taken as a lookup table map. In such a case, errorwould then drop to the repeatability error.

The advantage of having a system that may be easily calibrated is thatthe manipulator could be calibrated automatically using a built-invision system for example, at regular intervals. Aging of the polymericmaterial can then be mitigated by this strategy during lifetime service,which is of great advantage.

FIG. 16 shows a comparison of a predicted path of the tip of the needleand the experimental validation obtained by a video. In the experiment,the resolution of the camera falls to less than 500 kpixel to obtain 30frames per second and the speed of the needle creates a shade around theend-effector which renders the image processing more difficult.

As illustrated, the theoretical model seems to overestimate thedisplacement of the end-effector, but the behavior of the system betweentwo positions is well represented. Error sources may be present in thesystem. In fact, the path may also be influenced by time dependentelements such as pneumatic flow resistance.

The repeatability of the prototyped device was of about 1.3 mm and hasbeen reduced to about 0.5 mm when using a reset sequence before reachinga targeted position. The accuracy of the system was evaluated bycomparing the experimental position of end effector to the predictedposition of the workspace for many actuation states. An average accuracyof 2.1 mm may be reached using proper calibration procedures, asexplained above.

It has also been demonstrated that the trajectory of the needle may bepredicted using the deformation energy of the PAMs. Experimentalvalidations show that the end-effector does not follow a rectilinearpath for all actuation state changes and is strongly affected bypneumatic restriction.

According to a further aspect, a method for manufacturing an integralmolded unit comprising a plurality of fluid actuated devices embeddedtherein as described above will now be described with reference to FIG.17.

A mold comprising a plurality of molding cavities for respectivelymolding the plurality of fluid actuated devices is provided, accordingto processing step 1710. In one embodiment, the mold may comprise alower and an upper aluminum half. Each half of the mold comprises aplurality of molding housings facing a corresponding molding housing inthe other half of the mold, each pair of facing molding housingsdefining a corresponding molding cavity devised to form a correspondingfluid actuated device therein.

According to processing step 1712, at least one wax insert is mounted onan elongated rod to provide a mounted rod.

According to processing step 1714, a mounted rod as previously describedis mounted in each of the plurality of molding cavities. In oneembodiment, the mounted rods are mounted in a selected half of the moldalthough other arrangements may be considered.

As it should become apparent to the skilled addressee, each of the fluidactuated devices will be molded inside the corresponding molding cavityaround the rod and the at least one wax insert.

According to processing step 1716, a polymer material mix, a siliconemix such as Silastic V-RTV Silicone from Dow Corning for example, isprovided.

According to processing step 1718, the polymer material mix is insertedin the mold until the mold is full. In one embodiment, the silicone mixmay be poured in the mold while, in an alternative embodiment, thesilicone mix may be injected with a plastic syringe and suitable tubingwhen required.

According to processing step 1720, the inserted polymer material mix isset to cure to form the integral molded unit, for example for 6 to 10hours at room temperature, although other arrangements may beconsidered.

Then, according to processing step 1722 the integral molded unit may beremoved from the mold, the rods and wax inserts still extending insideeach fluid actuated device.

According to processing step 1724, the integral molded unit is thenheated, for example inside an oven at about 138° C. for about 40minutes, during which time the wax melts. The skilled addressee willindeed appreciate that silicone can withstand temperatures up to 150° C.for long periods of time. Others arrangements may be considered. Forexample, the heating period may range from 30 minutes to 50 minutes as anon-limitative example. The heating temperature may also range from 130degrees to 150 degrees although others arrangements may be consideredfor a given application and according to the material used.

According to processing step 1726, the rods are then removed from theintegral molded unit, for example by manually pulling thereon. Eachremoved rod provides an inlet hole in the corresponding molded fluidactuated device.

According to processing step 1728, the melted wax is also removed fromeach of the fluid actuated devices through the corresponding inlet holecreated by the rod. In one embodiment, the fluid actuated devices may besqueezed to help the wax flowing out therefrom.

In one embodiment, the molded integral unit is then put at rest during 7days before use thereof. This resting period, which may depend on thematerial used, may enable improved performances of the molded integralunit.

As previously detailed, in one embodiment, each of the molded fluidactuated devices may be provided with at least one internalreinforcement rib in order to limit radial deformation of the fluidactuated device.

In order to form these reinforcement ribs, in one embodiment, aplurality of wax inserts may be mounted in a space-apart relationship onthe rod. During filling of the mold, silicone will spread inside thecavities and fill the spaces defined between two consecutive waxinserts. Once the wax is removed, an integral molded unit comprisinginner integrally molded reinforcement ribs such as the one shown in FIG.6 may be obtained.

In a further embodiment, a first and a second permanent end inserts maybe mounted at each end of the mounting rod. These two permanent endinserts, which may be made of plastic for example, will remainpermanently inside the fluid actuated devices once such fluid actuateddevices will be removed from the mold.

The skilled addressee will appreciate that the above described methodfor manufacturing an integral molded unit comprising a plurality offluid actuated devices embedded therein is of great advantage forreducing manufacturing costs of the set of fluid actuated devices.

Moreover, such manufacturing method may enable to reduce manufacturingand assembly errors, therefore improving the accuracy of the wholedevice. This also helps to even reduce the size of the overallintegrated device for orienting.

Although a specific embodiment has been described, the skilled addresseewill nevertheless appreciate that various other configurations may beenvisaged for a given application, in the medical sector or in any otherfield wherein an accurate positioning of an object is required.

For example, the device may be used in a MRI environment as well as in acomputed tomography environment or other various imaging environments.As non-limitative examples, the device may be used for biopsy orbrachytherapy treatments.

Moreover, even if well adapted for prostate treatment, it may also beused for the treatment of kidney, liver, cervix uteri, pancreas,gallbladder, capsule tumor, as well as for the stimulation of thecardiac muscle, angiography or even cerebral cartography asnon-limitative examples.

Furthermore, the skilled addressee will appreciate that the device fororienting may also be used in several types of prosthesis, in devicesfor movement assistance or even in systems for positioning andmaintaining given anatomical structures during clinical interventions.

The integrated device for orienting may be manufactured at a low cost,which is of great advantage for reducing the overall medical costsassociated to a clinical intervention.

Although the above description relates to specific preferred embodimentsas presently contemplated by the inventors, it will be understood thatthe invention in its broad aspect is not limited to these specificembodiments and includes mechanical and functional equivalents of theelements described herein.

1. An integrated device for orienting an object according to a givenspatial orientation, said device comprising: a frame; a supportingmember adapted for supporting a portion of said object, said supportingmember being operatively connected to the frame; a plurality of fluidactuated devices integrally molded and joined together through a joiningportion to form an integral unit, each of said fluid actuated deviceshaving a first end operatively connected to the frame and a second endoperatively connected to the supporting member, each of said fluidactuated devices being actuatable between a first position wherein thefluid actuated device has a first length and a second position whereinthe fluid actuated device has a second length; and an actuationmechanism comprising a plurality of actuating valves, each beingrespectively operatively connected to a corresponding fluid actuateddevice for actuating said corresponding fluid actuated device betweensaid first position and said second position; wherein an actuation of atleast one of said fluid actuated devices enables to displace thesupporting member with respect to the frame to thereby orient saidobject according to said given spatial orientation.
 2. (canceled) 3.(canceled)
 4. (canceled)
 5. (canceled)
 6. (canceled)
 7. (canceled) 8.The integrated device for orienting an object according to claim 1,wherein the plurality of fluid actuated devices is distributed in aparallel array in a star-like shape, the joining portion extendingcentrally in the star like shape and being adapted for mounting with thesupporting member.
 9. (canceled)
 10. The integrated device for orientingan object according to claim 1, wherein the first end of each of thefluid actuated devices comprises an attaching element integrally moldedtherewith and adapted for attaching to a corresponding attaching elementprovided on the frame.
 11. (canceled)
 12. (canceled)
 13. The integrateddevice for orienting an object according to claim 1, wherein the secondend of each of the fluid actuated devices is integrally molded to thejoining portion.
 14. (canceled)
 15. (canceled)
 16. The integrated devicefor orienting an object according to claim 1, wherein each of the fluidactuated devices comprises a longitudinal operating body and at leastone inner radial reinforcement rib distributed therealong. 17.(canceled)
 18. (canceled)
 19. (canceled)
 20. (canceled)
 21. Theintegrated device for orienting an object according to claim 1, whereineach of said fluid actuated devices is mounted on a given plane fordisplacing said supporting member on said plane, the device fororienting an object further comprising an additional plurality of fluidactuated devices arranged on a second plane, spaced-apart from the givenplane, and an additional supporting member mounted on the second planefor supporting at least another portion of said object.
 22. (canceled)23. (canceled)
 24. (canceled)
 25. The integrated device for orienting anobject according to claim 21, wherein the position sensor comprises athree degree of freedom Dielectric Elastomer Actuator (DEA) sensor basedon capacitance measurement.
 26. The integrated device for orienting anobject according to claim 25, wherein the Dielectric Elastomer Actuator(DEA) sensor comprises a rigid circular outer frame and an array ofsector-shaped compliant electrodes attached thereto, the DielectricElastomer Actuator (DEA) sensor further comprises an inner mounting ringattached to each compliant electrode for receiving a portion of theobject therein.
 27. (canceled)
 28. (canceled)
 29. The integrated devicefor orienting an object according to claim 1, wherein each of theactuating valves comprises a Dielectric Elastomer Actuator (DEA). 30.The integrated device for orienting an object according to claim 1,wherein each of the actuating valves comprises a jet-valve driven by abistable rotary Dielectric Elastomer Actuator (DEA).
 31. The integrateddevice for orienting an object according to claim 1, wherein each of theactuating valves comprises: a valve body; a jet assembly mounted withthe valve body; a bistable rotary Dielectric Elastomer Actuator (DEA)mounted with the valve body for operating the jet assembly, the bistablerotary Dielectric Elastomer Actuator (DEA) comprising: a rigid frame; amoving element having first and second ends, the first end beingpivotally attached to the rigid frame for enabling pivoting of themoving element between a first position and a second position thereof;and a first and a second Dielectric Elastomer Actuator (DEA) films, eachbeing attached between the second end of the actuating element and therigid frame in a antagonistic facing relationship in a pre-stretchedstate, an actuation of a corresponding one of the Dielectric ElastomerActuator (DEA) films enabling rotating the moving element between thefirst and the second position.
 32. The integrated device for orientingan object according to claim 1, wherein the actuating valves areembedded in an integrated polymer air valves stack.
 33. (canceled) 34.The integrated device for orienting an object according to claim 1,wherein the plurality of fluid actuated devices is operatively connectedbetween the frame and the supporting member and is adapted to enable anelastically averaged positioning of the supporting member. 35.(canceled)
 36. The integrated device for orienting an object accordingto claim 1, wherein the object is selected from a group consisting of amedical needle, a trocart and an electrode.
 37. The integrated devicefor orienting an object according to claim 1, wherein the objectcomprises a medical device for insertion of a therapeutic agent into ananatomical structure, said therapeutic agent being selected from a groupconsisting of a radioactive material, a cryogenic agent and achemotherapy agent.
 38. (canceled)
 39. (canceled)
 40. A DielectricElastomer Actuator (DEA) valve comprising: a valve body; a jet assemblymounted with the valve body; a bistable rotary Dielectric ElastomerActuator (DEA) mounted with the valve body for operating the jetassembly, the bistable rotary Dielectric Elastomer Actuator (DEA)comprising: a rigid frame; a moving element having first and secondends, the first end being pivotally attached to the rigid frame forenabling pivoting of the moving element between a first position and asecond position thereof; and a first and a second Dielectric ElastomerActuator (DEA) films, each being attached between the second end of theactuating element and the rigid frame in a facing antagonisticrelationship in a pre-stretched state, an actuation of a correspondingone of the Dielectric Elastomer Actuator (DEA) films enabling rotatingthe moving element between the first and the second position.
 41. Amethod for manufacturing an integral molded unit comprising a pluralityof fluid actuated devices embedded therein, said method comprising:providing a mold comprising a plurality of molding cavities forrespectively molding the plurality of fluid actuated devices; mountingat least one wax insert on an elongated rod to provide a mounted rod;mounting a corresponding mounted rod in each of the plurality of moldingcavities; providing a polymer material mix; inserting the polymermaterial mix in the mold; curing the inserted polymer material mix toform the integral molded unit; removing the integral molded unit fromthe mold; heating the integral molded unit at a given heatingtemperature for melting each of the at least one wax insert; removingthe rods from the integral molded unit, each removed rod providing aninlet hole in the corresponding molded fluid actuated device; andremoving the melted wax from each of the fluid actuated devices throughthe corresponding inlet hole.
 42. (canceled)
 43. (canceled)
 44. Themethod for manufacturing an integral molded unit according to claim 41,wherein the inserting of the polymer material mix comprises pouring thepolymer material mix in the mold.
 45. The method for manufacturing anintegral molded unit according to claim 41, wherein the inserting of thepolymer material mix comprises pouring the polymer material mix in themold.
 46. The method for manufacturing an integral molded unit accordingto claim 41, wherein the inserting of the polymer material mix comprisesinjecting the polymer material mix in the mold with a syringe. 47.(canceled)
 48. (canceled)
 49. (canceled)
 50. The method formanufacturing an integral molded unit according to claim 41, wherein thegiven heating temperature ranges between 130 and 150 degrees.
 51. Themethod for manufacturing an integral molded unit according to claim 41,wherein the removing of the melted wax from each of the fluid actuateddevices is performed by squeezing each of the fluid actuated devices.52. The method for manufacturing an integral molded unit according toclaim 41, wherein the at least one wax insert comprises a plurality ofwax inserts mounted in a space-apart relationship for enabling formingan inner integrally molded reinforcement rib between two adjacent waxinserts.
 53. The method for manufacturing an integral molded unitaccording to claim 41, wherein the mounting of at least one wax inserton an elongated rod further comprises mounting a first and a secondpermanent end inserts at each end of the corresponding mounting rod.